Leaf spring compression system design

Abstract

A leaf spring compression system comprising a mechanical assembly for securing a plurality of leaf springs on a battery cell stack of a flow battery system is disclosed. The cell stack may, comprise: a plurality of cells stacked together to form a flow battery; and a compression system comprising at least two tie rods extending through the plurality of cells clamping a spring acting at opposite ends to compress the cells together, the spring contacting at least two fulcrum elements positioned between the tie rods. In this way, the compression system may exert uniform loading on the battery cell stack, while minimizing deflection of pressure plates attached to the cell stack.

The invention claimed is: 
     
       1. A cell stack, comprising:
 a plurality of cells stacked together to form a flow battery; and 
 a compression system comprising:
 pressure plates positioned on opposing ends of the plurality of cells; 
 tie rods extending through the plurality of cells and the pressure plates; 
 a spring acting on each pressure plate to compress the plurality of cells together; 
 at least two fulcrum elements positioned between a respective spring and pressure plate and interior to the tie rods. 
 
 
     
     
       2. The cell stack of  claim 1 , further comprising one or more bars positioned between the respective spring and pressure plate and extending between a pair of tie rods;
 wherein the at least two fulcrum elements are positioned between a respective bar and spring and the least two fulcrum elements are movable when the compression is released. 
 
     
     
       3. The cell stack of  claim 2 , wherein the spring is a leaf spring comprising one or more leaf spring elements. 
     
     
       4. The cell stack of  claim 3 , wherein the one or more leaf spring elements include a planar rectangular bar having a length longer than a width longer than a thickness. 
     
     
       5. The cell stack of  claim 1 , wherein the tie rods are threaded and tightened via rotation about their central longitudinal axis. 
     
     
       6. The cell stack of  claim 1 , wherein only a pair of the at least two fulcrum elements is mated with only a pair of tie rods, where a plurality of the mated pairs of tie rods and fulcrums compresses the cell stack. 
     
     
       7. The cell stack of  claim 1 , wherein the at least two fulcrum elements are positioned between an exterior wall formed by one or more of the plurality of cells and an interior wall of the spring. 
     
     
       8. The cell stack of  claim 1 , wherein the at least two fulcrum elements are selected to more evenly distribute load created by the spring across the cell stack in a direction of a length direction of the spring than if no fulcrum elements were provided. 
     
     
       9. The cell stack of  claim 1 , wherein each cell is rectangular in shape and stacked with a shortest edge having a thickness and aligning with other edges of other cells to form a wall of the cell stack, the tie rods extended through the plurality of cells in a direction of the thickness. 
     
     
       10. The cell stack of  claim 1 , wherein a plurality of singular springs and pairs of the tie rods and pairs of the at least two fulcrum elements compress the cell stack, wherein the plurality of singular springs are planar and all lie in a common plane, and the tie rods are all aligned in parallel with each other. 
     
     
       11. A system, comprising:
 a flow battery having a plurality of cells in a cell housing stacked together; 
 pressure plates on opposing ends of the plurality of cells; 
 tie rods extending through the plurality of cells and the pressure plates, the tie rods extending in parallel with each other and clamping a spring acting at an end of the plurality of cells to compress the plurality of cells together; and 
 the spring contacting at least two fulcrum elements positioned between the spring and a respective pressure plate and interior to the tie rods. 
 
     
     
       12. The system of  claim 11 , wherein the flow battery further includes plugs inserted through apertures on a face of the cell housing to block the apertures on the cell housing. 
     
     
       13. The system of  claim 11 , further comprising one or more bars positioned between the spring and the respective pressure plate and extending between a pair of tie rods; and
 wherein the at least two fulcrum elements are positioned between the one or more bars and the spring and the at least two fulcrum elements are movable when the compression is released; and 
 wherein the spring is a leaf spring comprising one or more leaf spring elements. 
 
     
     
       14. The system of  claim 13 , wherein the one or more leaf spring elements include a planar rectangular bar having a length longer than a width longer than a thickness. 
     
     
       15. The system of  claim 13 , wherein the tie rods are threaded and tightened via rotation about their central longitudinal axis. 
     
     
       16. The system of  claim 15 , wherein only a pair of the at least two fulcrum elements is mated with only a pair of tie rods, where a plurality of the mated pairs of tie rods and the at least two fulcrum elements compresses the stacked plurality of cells. 
     
     
       17. The system of  claim 16 , wherein the at least two fulcrum elements are positioned between an exterior wall formed by one or more of the plurality of cells and an interior wall of the spring. 
     
     
       18. The system of  claim 17 , wherein each cell is rectangular in shape and stacked with a shortest edge having a thickness and aligning with other edges of other cells to form a wall of the stacked plurality of cells, the tie rods extended through the plurality of cells in a direction of the thickness. 
     
     
       19. The system of  claim 18 , wherein a plurality of singular springs and pairs of the tie rods and pairs of at least two fulcrum elements compress the stacked plurality of cells, wherein the plurality of singular springs are planar and all lie in a common plane, and the tie rods are all aligned in parallel with each other. 
     
     
       20. A system, comprising:
 a flow battery having a plurality of cells in a cell housing stacked together; and 
 pressure plates on opposing ends of the plurality of cells; 
 tie rods extending through the plurality of cells and the pressure plates, the tie rods clamping a spring acting at an end to compress the plurality of cells together; and 
 the spring contacting at least two fulcrum elements positioned between the spring and a respective pressure plate and interior to the tie rods, 
 wherein the at least two fulcrum elements are movable when the compression is released, 
 wherein the spring is a leaf spring comprising one or more leaf spring elements, 
 wherein a plurality of singular springs and pairs of tie rods and pairs of at least two fulcrum elements compress the stacked plurality of cells, 
 wherein the plurality of singular springs are planar and all lie in a common plane, and the tie rods are all aligned in parallel with each other.